Diamorphs

Werewolves, vampires, ghosts, and frogmen. They're all the same thing, when you get down to it, just a basic perversion of humans through old fashion rituals. And they're unstable, you know, like they're barely held together. Fail to put in the right energy - whether that's blood or sunlight or what have you - and the poor things's start coming apart at the seams.

"Diamorphs" is a group term which refers to any of a number of sub-expressions: the most commonly known of these are vampires, werewolves, etc.
All "diamorphs" begin as human, and are converted to a diamorph state by some kind of magical ritual. It is possible, but extremely unusual for this to happen by accident. Usually it is the result of a magical practitioner or sorcerer carefully following a ritual (often involving artifacts and rune-engraved crystals and a power source)

The source of the rituals

Many of these rituals date from ancient times, when sorcery was more understood and had not been suppressed by various religions. Sumerian, ancient Egyptian, ancient Greek origins are all common. Some rituals have been handed down for generations by traditional communities untouched by churches, like deep-island Hawaiian traditions, African traditions, Indian traditions, and native American traditions.

Types of power sources

Power source types include solar energy, blood, lunar energy, magical energy, electricity, heat, kinetic energy.

Chances and consequences of failure

There are several possible outcomes of a diamorph ritual, the specifics of qhich depend on the ritual in question.
A successful outcome converts the target of the ritual into the desired diamorph. Diamorphs can be more or less strong, and more or less energy efficient. They will still need input of the correct energy source to keep them stable.
An unsuccessful outcome can result in a partially-converted subject, which quickly becomes unstable and dies, or rarely, is driven mad by being stuck between two states.
Rarely (and less-rare for certain rituals, like the Vampiric ritual), the diamorph ritual can create a monster instead of a diamorph. Examples of this include Blood Demons in the vampiric ritual, and harpies in the ritual of new life. The reasons for this catastrophic change vary, but the result is a creature which is both insane and very strong, and usually is put down by the SEdGen, The Knights of St John or a similar organization.

Type

Magical